For the sambal, mix together the onion, chillies and micro coriander and set aside.
For the curry cream, heat the oil in a medium sauté pan over a medium heat and gently fry the vegetables, apple, coriander stalks and spices for a few minutes until soft. Add the stock and coconut cream, bring to the boil and simmer for 2–3 minutes.
Blitz the mixture in a blender, pass through a sieve, reserving the cream in a bowl underneath, and keep warm.
To make the flatbreads, mix together the flour, baking powder, yoghurt and oil and knead until a soft dough is formed (you may need to add a little water if the dough is too dry). Divide the dough into four equal portions and roll out on a floured surface to approximately 1cm/½in thick.
Heat a griddle pan over a medium heat and grill the flatbreads for 2–3 minutes on each side, until lightly browned.
Meanwhile, heat the oil in a frying pan and fry the mackerel fillets for 2–3 minutes on each side, or until cooked through.
Melt the butter, then mix with the anchovies, garlic and coriander leaves. Brush the mixture over the hot flatbreads.
To serve, pour the curry cream into the bottom of four serving bowls and sprinkle over the sambal. Top with the mackerel and micro coriander and serve with the flatbreads.